Calculation of core electron binding energies from structural formulas

We propose a simple algorithm that relates core ionization energy shifts to the expression Σ_iN_cⁱa_i, where N_cⁱ is calculated from a structural formula. The constants a_i are considered typical for each element i and are determined by a least-squares fit to already available experimental data. A numerical demonstration is performed for the fluorine 1s core ionization energies of compounds with 2-10 atoms and for C1s core ionization energies of alkanes. Different formulas for expressing shifts in external polarizabilities are presented and discussed.